| Acute myocardial infarction(AMI)is a serious type of cardiovascular diseases.According to information from the China Health and Family Planning Statistical Yearbook in recent years,cases of acute myocardial infarction in China are increasing year by year.It is characterized by rapid onset,critical condition and poor prognosis.When acute myocardial infarction occurs,the earlier the intervention is carried out,the better the prognosis of the patient.The diagnostic markers of acute myocardial infarction include cardiac enzymes,troponin,and myoglobin.These diagnostic markers are indicated for both acute myocardial infarction and other conditions associated with myocardial injury disease.Different markers of cardiac injury have different clinical significance.When cardiomyocytes are damaged,the cellular contents,including cardiac troponin(c Tn I),enter the bloodstream.Cardiac troponin is unique to cardiomyocytes and has excellent sensitivity and cardiac specificity.It is considered the "golden marker" for the diagnosis of acute myocardial infarction.Digital microfluidics(DMF)is a technique for manipulating droplets on a digital microfluidic chip based on the principle of dielectric wetting,which has developed rapidly in recent years.It allows for fast and automated detection operations on samples to be tested,greatly reducing detection time.Many researchers have adapted it to biosensing detection.In addition,digital microfluidic systems are highly integrated,which can reduce the complexity of the overall system.Usually,when assays are performed on digital microfluidic chips,magnetic nanoparticles are used as solid-phase carriers in order to effectively separate and enrich the target substances during the reaction.This study combines digital microfluidics,magnetic nanoparticles,and chemiluminescence detection technology to propose a digital microfluidics-based chemiluminescence detection system for the rapid,automated,and low-cost detection of c Tn I.This is expected to provide a solution for the rapid diagnosis,miniaturization,and automation of acute myocardial infarction in clinical settings.In this study,c Tn I was detected on a digital microfluidic chip using a double antibody sandwich immunological method.The c Tn I antigen in the sample to be tested is captured by magnetic nanoparticles encapsulated with c Tn I antibodies and then recognized by biotin-labeled c Tn I antibodies.Finally,the enzymatic labeling of c Tn I antigen is achieved by binding of catalase-labeled streptavidin to biotin.In our experiments,the catalase we chose was Horseradish Peroxidase(HRP).After the magnetic nanoparticles are washed,the HRP-labeled complex is obtained,i.e."c Tn I antibody-coated magnetic nanoparticles-c Tn I antigen-biotin-labeled c Tn I antibody-HRP-labeled streptavidin".The chemiluminescent reagent is added to the HRP-labeled complex,and the chemiluminescent reagent emits light under the catalytic effect of HRP.The intensity of chemiluminescence is measured and the concentration of c Tn I antigen in the sample to be tested is reflected by the intensity of luminescence.The "sandwich" immunoassay,in which the primary and secondary antibodies recognize the antigen simultaneously,and the high specificity of the reaction between streptavidin and biotin,make our system highly sensitive to c Tn I.The sensitivity and specificity of our system for c Tn I detection are greatly improved.In addition,we performed practical experiments on c Tn I samples.The results showed that the system has good stability(CV=2.26%)and specificity of the assay.Compared to conventional ELISA assays,the assay system can detect c Tn I in less than 40 minutes in an automated and low reagent consumption manner.The limit of detection(LOD)for c Tn I was 0.34 ng/m L,and it showed good linear correlation in the concentration range of 0.39 to25 ng/m L with a correlation coefficient of 0.994.The system is expected to be applied to the clinical determination of c Tn I in human serum. |
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